The Center for Expression Arrays (CEA) is a University of Washington research resource center that provides microarray services to the University of Washington and greater Seattle research communities. Since its inception, the CEA has processed over 4000 microarrays and has made microarray-based experiments available to dozens of labs that otherwise could not have afforded such experiments. In this proposal, we are requesting funds to upgrade our Affymetrix GeneChip Instrument System. This system upgrade will allow UW researchers to use Affymetrix 2.0 chips, which have a reduced feature size (11 fm) and contain approximately 50,000 features per chip. These new chips allow whole genomes to be assayed with a single hybridization. In addition, all future Affymetrix GeneChips will use the new feature size. Without the new instrument system, UW researchers will be unable to take advantage of new developments in the Affymetrix platform. This would be a great hindrance to research as many labs at the UW already have a history of using Affymetrix GeneChips and changing to a different platform would cost valuable time and would render comparisons to already completed datasets difficult, if not impossible. The Instrument System upgrade also will reduce the costs of microarray experiments to researchers, both because the cost on a per feature basis will be less and because the other upgrade components (chip autoloader and fluidics station upgrades) will allow greater efficiency in operation of the CEA. In sum, the new Instrument System is necessary to ensure that high quality microarray research continues at the University of Washington.